Short answers, pulled from the story.
A music genre is a conventional category that identifies pieces of music as belonging to a shared tradition or set of conventions. It is distinguished from musical form and musical style, though in practice the terms are sometimes used interchangeably.
In 1982 Franco Fabbri defined musical genre as a set of musical events, real or possible, whose course is governed by a definite set of socially accepted rules. This definition is now considered normative.
The proliferation of popular music in the 20th century has led to over 1,200 definable subgenres of music. A subgenre adopts a genre's basic characteristics while adding its own distinguishing traits.
A fusion genre is a musical composition that sits at the intersection of two or more genres, sharing characteristics of each parent genre and belonging to each at once. Examples include jazz fusion, blending jazz and rock, and country rock, blending country and rock.
Every Noise at Once is a categorical perception spectrum of genres and subgenres created by Glenn McDonald, an employee of The Echo Nest, a music intelligence and data platform owned by Spotify. It is an algorithmically generated, readability-adjusted scatter-plot based on 5,315 genre-shaped distinctions tracked by Spotify.
Personality, age, and social identity all influence music preference, with self-described rebels favoring heavy metal or hard rock and relaxed listeners favoring jazz or classical. One model proposes five genre-free factors, Mellow, Urban, Sophisticated, Intensity, and campestral, while a Canadian study found adolescents prefer pop and older listeners prefer rock, opera, and jazz.